let sum = (x, y) => x + y;
let succ = sum.bind(null, 1); // 将第一个参数绑定为 1
console.log(succ(2)); // 3

function f(y, z) {
  return this.x + y + z;
}
const g = f.bind({ x: 1 }, 2);
console.log(g(3)); // 6
console.log(g.name); // bound f
